U.S. Pat. No. 4,848,009 to Rodgers discloses a running shoe in which an external battery is connected, via a mercury switch, to a set of light-emitting diodes (LEDs) positioned about the exterior of the shoe sole. The shoe of the Rodgers patent additionally includes a timing circuit to limit the duration of the illumination. The timing circuit appears designed to counteract some of the detrimental effects of including a mercury switch in or on the shoe; otherwise, according to the Rodgers patent, the shoe may be subject to "loss of battery power if . . . stored in an attitude which would maintain switch closure for an extended period."
European Patent Application No. 83307822.3 of Dana III discusses another illuminated running shoe using an external push button switch to connect LEDs or other sources of light to a power source such as a battery. The Dana III application also discloses including a pressure-actuated switch (instead of or in addition to the push button switch), with the switch positioned within the sole of the shoe under the heel of the wearer. If used, the internal pressure-actuated switch closes when subjected to pressure from the wearer's heel.
Yet another illuminated shoe is illustrated in U.S. Pat. No. 2,572,760 to Rikelman. Included within the shoe of the Rikelman patent is a single lever on which a ball rides. Movement of the ball forces the lever to pivot in either of two directions, switching a lamp on when pivoted in one direction and off when pivoted in the other. To prevent premature loss of battery power, the shoe of the Rikelman patent contains a thumb screw that may be used to pivot and maintain the lever in the "off" position.
European Patent Application No. 89200784.0 of Intermedium B.V., finally, discloses footwear adapted for both optical and acoustical signalling. As with the shoe disclosed in the Dana III application, the footwear of the Intermedium B.V. application includes a pressure-sensitive switch within its heel portion. In use, the weight of the wearer's heel compresses air present in a reservoir within the shoe to close the pressure-sensitive switch, thereby activating a loudspeaker and a set of LEDs. Incorporated herein in their entireties by this reference are each of the Rodgers and Rikelman patents and the Dana III and Intermedium B.V. applications.